This application claims the priorities of Korean Patent Application Nos. 2002-62481 and 2003-56423, filed on Oct. 14, 2002, and Aug. 14, 2003, respectively, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a magnetic medium and an apparatus and method of recording data on the magnetic medium, and more particularly, to a magnetic medium using spin-dependent electron scattering and an apparatus and method of recording data on the magnetic media.
2. Description of the Related Art
In conventional data storage devices, if a magnetic medium is used as a recording medium, data is stored on the magnetic recording medium by reversing the direction of magnetization caused by a magnetic field. As the recording density of conventional data storage devices increases, a bit, the smallest data recording unit, becomes smaller, and accordingly, a magnetic field for recording data must be reduced so as to be focused on a small area corresponding to the bit. However, ironically, with an increase in the size of the magnetic anisotropy of a magnetic layer, the intensity of the magnetic field needed to reverse the magnetization of the magnetic layer must be increased.
To overcome this technical problem of the conventional art, U.S. Pat. No. 6,304,481 discloses a method and apparatus for storing data using spin-polarized electrons.
FIG. 1 is a cross-sectional view of the data storage apparatus disclosed in the above U.S. Patent. Referring to FIG. 1, the disclosed data storage apparatus includes a control unit 1, a spin-polarized electron source 40 having a tip 2b, an extractor 4, collimators 6, 7, and 9, electrostatic lenses 10, 11, and 12, and insulating elements 5 and 8. The data storage apparatus also includes a blanking element 13, coarse and fine microdeflectors 14 and 15, respectively, an electron detector 16, a data storage layer 17, and a substrate 18.
The control unit 1 receives control signals and data from an external device (not shown) via ADDRESS IN, DATA IN, and DATA OUT terminals, and decodes the received control signals and data using necessary protocols. The control unit 1 develops control responses and data and returns them to the external device.
The electron source 40, including the tip 2b, provides spin-polarized electrons 3, and the tip 2b collects them. The extractor 4 extracts the spin-polarized electrons 3 from the tip 2b, and the collimators 6, 7, and 9 collimate the spin-polarized electrons 3 into a spin-polarized electron beam 19. The electrostatic lenses 10, 11, and 12 focus the spin-polarized electron beam 19, and the coarse and fine microdeflectors 14 and 15, respectively, direct the spin-polarized electron beam 19 toward a magnetic field generated within part of the data storage layer 17, where data is to be stored.
The data storage layer 17 includes a plurality of alignment areas 22 and an electrically conductive material 27 electrically insulated from the data storage layer 17 by an insulator 28.
The control unit 1 applies a potential V1 to the electron source 40 and also applies potentials V2-V5 to the electron source 40 to obtain desired characteristics of the spin-polarized electrons 3 and the spin-polarized electron beam 19. Potentials V6-V8 are applied to the electrostatic lenses 10, 11, and 12, respectively, by the control unit 1 to create electrostatic fields through lens apertures. Potentials V12-V19 are applied to one end of a stigmator element 25 by the control unit 1. The control unit 1 applies a signal S19 to the electron source 40 to determine the direction of spin polarization of the spin-polarization electrons 3, and also applies signals S2-S9 and S10-S17 to the coarse and fine microdeflectors 14 and 15, respectively, to direct the spin-polarized electron beam 19 toward the data storage layer 17. Also, the control unit 1 applies a signal S1 to the blanking element 13 and alternately detects signals S18 and S20 to read data therefrom.
The disclosed data storage apparatus have to minutely adjust potentials to focus an electron beam onto a specific data area. The minute adjustment of potentials is not easy, and accurate output of signals where data has been recorded is not easy either, which makes data reproduction difficult. Also, due to the use of conventional magnetic media, there is a limit to increasing the data recording density of the magnetic media, and the disclosed data storage apparatus has a complicated structure.